Neuromorphic circuit capable of setting negative weights and back propagation

Abstract

Provided is a neuromorphic circuit including an input module configured to generate an input voltage, an output module configured to measure a current transmitted from the input module and generate an output voltage, synapse modules configured to electrically connect the input module and the output module and determine a current to be transmitted to the output module and including a memory element to which a weight is assigned, and a crossing module configured to control a direction of current flowing through the synapse modules.

What is claimed is: 
     
         1 . A neuromorphic circuit comprising:
 an input module configured to generate an input voltage;   an output module configured to measure a current transmitted from the input module and generate an output voltage;   synapse modules configured to electrically connect the input module and the output module and determine a current to be transmitted to the output module, the synapse modules each including a memory element to which a weight is assigned; and   a crossing module configured to control a direction of current flowing through the synapse modules,   wherein the crossing module includes four switches configured to selectively connect the input module and the output module to opposite sides of the synapse modules, including a first switch connecting the input module to a first terminal of a synapse module, a second switch connecting the output module to a second terminal of the synapse module, a third switch connecting the input module to the second terminal of the synapse module, and a fourth switch connecting the output module to the first terminal of the synapse module, and   wherein during a forward propagation mode the first and second switches are turned on while the third and fourth switches are turned off, and during a back propagation mode the third and fourth switches are turned on while the first and second switches are turned off, thereby permitting current to flow only through selected connections.   
     
     
         2 . The neuromorphic circuit of  claim 1 ,
 wherein the forward propagation mode sets a current to flow through the synapse modules in a first direction, and the back propagation mode sets the current to flow through the synapse modules in a second direction opposite to the first direction.   
     
     
         3 . The neuromorphic circuit of  claim 2 ,
 wherein the crossing module is configured to transmit a current to the output module according to a synapse module connected to a column line in the forward propagation mode, and according to a synapse module connected to a row line in the back propagation mode.   
     
     
         4 . The neuromorphic circuit of  claim 3 ,
 wherein the crossing module is configured to transmit a current to the output module according to a synapse module connected to a column line in the forward propagation mode and according to a synapse module connected to a row line in the back propagation mode.   
     
     
         5 . The neuromorphic circuit of  claim 1 ,
 wherein, when one or more input modules and a plurality of output modules are provided, the crossing module is configured to select output modules, a number of which is equal to a number of the one or more input modules and to pair and connect the selected output modules and the one or more modules.   
     
     
         6 . The neuromorphic circuit of  claim 1 ,
 wherein, when one or more input modules and a plurality of output modules are provided, the synapse modules are arranged in row lines, a number of which is equal to a number of the one or more input modules, and in column lines, a number of which is equal to a number of the plurality of output modules.   
     
     
         7 . The neuromorphic circuit of  claim 6 ,
 wherein, when the number of the column lines and the number of the row lines are equal to each other, weights assigned to one or more synapse modules arranged in one or more row lines of one of the column lines are configured to cross weights assigned to one or more synapse modules arranged in one or more row lines of another of the column lines.   
     
     
         8 . The neuromorphic circuit of  claim 6 ,
 wherein, when the number of the column lines is greater than the number of the row lines, weights assigned to synapse modules are configured to cross each other in column lines, the number of which is equal to the number of the row lines among the column lines.   
     
     
         9 . The neuromorphic circuit of  claim 8 ,
 wherein an arbitrary weight is assigned to the synapse modules in the column lines, the number of which is greater than the number of the row lines.   
     
     
         10 . The neuromorphic circuit of  claim 6 ,
 wherein the number of the synapse modules arranged in the column lines is less than or equal to the number of the synapse modules arranged in the row lines.